WebApp Sec mailing list archives
RE: Tying a session to an IP address
From: "Wolf, Yonah" <Yonah.Wolf () ujc org>
Date: Mon, 10 May 2004 10:26:49 -0400
Paul, I tried this approach a few years ago, and got stymied by the very same logic that you are posing - some web caches are loadbalanced and although most of them can be programmed to take advantage of session stickiness, they don't. In addition, we have even run into cases of Session-sharing - i.e. two people behind the same proxy get the same sessionID - thereby further limiting the application of IP-based controls. Based on the way you are stating this problem, I am going to assume that Server-level authentication and/or client certificates are not going to work - it sounds like we are talking about a public web site. In the past I have heard people wanting to use the HTTP_X_PROXY_FOR header to determine the internal ip address - but that isn't standard across proxies TTBOMK. Bear in mind - if two people are at a Wi-Fi hotspot, it is not inconceivable that one can intercept the other's cookie and then use it to authenticate himself because he is coming from the same proxy. HTH, --Yonah -----Original Message----- From: Paul Johnston [mailto:paul () westpoint ltd uk] Sent: Monday, May 10, 2004 9:14 AM To: webappsec () securityfocus com Subject: Tying a session to an IP address Hi, I'm interested in the merits of restricting a session to an IP address. I realise this isn't great security as often many users will appear to come from the same IP address (NAT, proxies, etc.) However, if you consider the case where an attacker uses an XSS vulnerability to steal the session ID, then the IP address restriction raises the bar considerably for an arbitrary remote attacker to exploit this. I'm worried that the IP address restriction wouldn't work for all users - e.g. if their ISP uses load-balanced web caches. Does anyone know how common such arrangements are in practice? Perhaps something to be done then is just check the top 16 bits of the IP address. This is likely to work for all such network arrangements and still raises the bar a lot for remote attacks. Does anyone here already restrict sessions by IP address? Regards, Paul -- Paul Johnston Internet Security Specialist Westpoint Limited Albion Wharf, 19 Albion Street, Manchester, M1 5LN England Tel: +44 (0)161 237 1028 Fax: +44 (0)161 237 1031 email: paul () westpoint ltd uk web: www.westpoint.ltd.uk
Current thread:
- Re: Tying a session to an IP address, (continued)
- Re: Tying a session to an IP address Rogan Dawes (May 10)
- Re: Tying a session to an IP address exon (May 10)
- Re: Tying a session to an IP address Rogan Dawes (May 10)
- Re: Tying a session to an IP address Chris Burton (May 10)
- Re: Tying a session to an IP address Imre Kertesz (May 10)
- Re: Tying a session to an IP address [summary] Paul Johnston (May 12)
- RE: Tying a session to an IP address Mike Randall (May 10)
- RE: Tying a session to an IP address Imperva Application Defense Center (May 10)
- Re: Tying a session to an IP address T.J. (May 10)
- Re: Tying a session to an IP address Adam Tuliper (May 10)
- RE: Tying a session to an IP address Steve McCullough (May 11)
- RE: Tying a session to an IP address Wolf, Yonah (May 10)
- RE: Tying a session to an IP address Scovetta, Michael V (May 10)
- Re: Tying a session to an IP address exon (May 10)
- Re: Tying a session to an IP address Mark Foster (May 10)
- Re: Tying a session to an IP address exon (May 10)
- RE: Tying a session to an IP address Tom Arseneault (May 10)
- RE: Tying a session to an IP address Toni Heinonen (May 10)
- Re: Tying a session to an IP address exon (May 10)
- RE: Tying a session to an IP address Tom Martin (May 11)